Advantages and Disadvantages of a High Frequency

Discussion in 'Homework Help' started by David Waddell, Feb 24, 2015.

  1. David Waddell

    Thread Starter New Member

    Dec 3, 2014
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    Hello

    Just looking to know what the main advanagtes and disadvanatages of a high frequency in a circuit. ( 7400 Series and 4000 Series). Just looking for some background information to my assignment.
     
  2. MrChips

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    Oct 2, 2009
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    At high frequency, logic circuits run faster, consume more power, generate more heat and more circuit noise.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    What's your assignment?
    The higher the frequency, the shorter the time to process a specific digital function, with a higher frequency causing the effects noted by MrChips.
    Another problem with very high frequencies is that the PCB layout and grounding becomes more critical.
     
  4. David Waddell

    Thread Starter New Member

    Dec 3, 2014
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    what if they run in CMOS?
     
  5. WBahn

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    Mar 31, 2012
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    4000 series logic IS CMOS.
     
  6. David Waddell

    Thread Starter New Member

    Dec 3, 2014
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    not all 7400 series families are CMOS
     
  7. WBahn

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    Mar 31, 2012
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    So?

    You asked about 7400 series logic and 4000 series logic and you got an answer that did not distinguish between them. Since 4000 series logic IS a CMOS family, why don't you think the answer applies to CMOS?
     
  8. David Waddell

    Thread Starter New Member

    Dec 3, 2014
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    Because CMOS circuits use less power, so I wanted to confirm that he wasn't talking generally about frequency
     
  9. MrChips

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    74C00 series is CMOS. Also 74HC00 series.

    What I said applies to all logic, CMOS and non-CMOS technology.

    Have you noticed that as PCs run at faster clock speeds the heat sinks on the CPU are getting bigger. The PCs generate more heat and the fans have to work harder to keep the mother board cool.
     
    Last edited: Feb 24, 2015
  10. crutschow

    Expert

    Mar 14, 2008
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    7400 TTL logic uses bipolar transistors, takes a lot of static power and that power only goes up slightly with frequency.
    74#C#00 and CD4000 series logic are CMOS and take very little static power but the power goes up with frequency since most of the power goes into charging/discharging circuit capacitances and that power is a linear function of frequency.
     
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